Plotter indicator for harbor defense



Sept. 3, 1946. E. w. SPRINGER PLOTTER INDICATOR FOR HARBOR DEFENSE 2Sheets-Sheet 1 f INVENTOR Filed April 9, 194:5

Sept. 3, 1946. E. w. SPRINGER PLOITER INDICATOR FOR HARBOR DEFENSE FiledApril 9, 1943 2 Sheets-Sheet 2 INVENTOR E 311 W. 515117111521" BY 7 J1PROJECTO R DETECTOR nmvsn Patented Sept. 3, 1946 PLOTT'ER INDICATOR FOR;HARBOR DEFENSE Earl W. Springer, Silver Hill, Md.

Application April 9, 1943, Serial No. 482,509

(Granted under the act of March 3,. 1883, as amended April30, 1928; 3700. G. 757) 8 Claims.

This invention relates to a plotter indicator for harbor. defense, and,has for'an object to provide av plotter indicator for use in connectionwith an offshore echo ranging system, particularly in tended: for usein. watching limited areas such as harbors,.river mouths, etc., todetect, the presence of any unauthorized submarine or vessel attempting.to enter the area under water or in fog or darkness;

A further object of this invention is toprovide an indicator fordetecting and indicating the range and. azimuth of any object withinsuchharbor area, as well: as to enable any moving; object in such area. to;be immediately detected. and to have: the range. and. azimuth of itsmovement' plotted so. that if the object be an unfriendly vessel orsubmarine: it may immediately be attacked and destroyed or captured.

A further object'- of this invention: isto provide a means forsimultaneously: indicating the range and azimuth of an unknown objectonthe same plotting indicator, which indicator may already have plottedthereon the range and azimuth of all known objects in the area, thusmaking it possible to realize immediately the presence of an unknownobject in the area.

Still a further object of this invention is to provide a harbor echorange and azimuth: listening device which utilizes a supersonicprojector anddetector placed at a suitable location in the area to bedetected, and controlled by and connected to the plotterindicator, acontrol means being located at a suitable shore station nearby.

With the foregoing and other objects in view, the invention consists inthe construction, combination and arrangement of parts hereinafterdescribed and illustrated in the drawings, in which:

Fig. 1 is an elevational front plan view of the plotter indicator.

Fig. 2 is a side edge view of Fig. 1, partly in section and on a largerscale.

Fig. 3 is a fragmentary partly sectional view of the front of theplotter indicator, similar to Fig. I, on the scale of Fig. 2.

Fig. 4 is a fragmentary view similar to Fig. 2, on. a, still largerscale, and partly in cross-section.

Fig. 5 is a front plan view of the belt partly broken away and itsoperating mechanism.

Fig. 6 is a sectional view on line 6-6 of Fig. 4.

Fig. 7 is a perspective view of a fragment of the belt, including thecontacting operating bosses thereon; and

Fig. 8 is a schematic outline and wiring assembly of the entire device.

There is shown at In the plotter indicator of this invention, whichincludes a box It for containing the shore station mechanism, at thefront of which is a dial l2 provided with azimuth indications l-3thereabout. Located an opening in dial [2 is a dial face 14 providedwith range indicated circles [-5 thereon commencing at the edge of acenter spot l6 and extending radially thereof. Asshown, the dial azimuthindications 13 are in degrees. from 0 to 360, the 0360 point beingmarked N. for north with the other three cardinal points similarlyindicated. The indication circles [:5 are each marked oif in ranges of1,000 yards up to 4,000 yards at the outermost circle, although itwilllbeunderstood that greater range areas could be indicatedthereon ifnecessary. However, it has been found in practice that it is probablymore desirable to use additional' indicators for ranges beyond 4,000yards.

The dial face [4 is made of frosted glass or other translucent material:suitable for receiving a crayon or pencil. marking thereon. Mounted on abracket l1" within the box l l behind the translucent dial face I4 is abearing [8 through which extends a hollow shaft 20, fixed to one end ofwhich is a largegear 21 meshed to a small gear 22 on the shaft 23' of aself-synchronous motor 24, this self-synchronous motor 24 beingcomplementary to a similar motor in a projector-detector member 58. Theother end of the shaft 20- has a supporting arm 26 mounted thereon andextending in one direction therefrom, while a counterweight arm 21extends in the opposite direction so as to balance the weight carried bythe shaft 20.

Extending through the center of the hollow shaft 20 is a shaft 28 fromthe motor 30 attached to beveled gear 3|; This gear 3-] is in mesh witha beveled gear 32 on a shaft 33 having a sprocket 34 so that therotation of the motor 30 will cause the sprocket 34 to rotate at acorresponding, speed. The shaft 33- of the sprocket 34 is mounted inbearings supported on the supporting arm 26. A corresponding sprocket 35at the upper end of the supporting arm 26 serves with the sprocket 34 tocarry a belt 36 thereon, this belt 36 having perforations 31' thereon tokeep it properly aligned on the sprocket teeth 38 of the sprockets 34and 35. This belt 36 is an endless belt and is provided with two windows40 thereon, the windows 40 being spaced an equal distance apart fromeach other on the belt.

Also mounted on the supporting arm. 20. is a neon flash tube 4| somounted. thatit is closely adjacent the portion of the belt 36 thatcomes closest to the back of the translucent dial face I4. The neonflash tube 4| is provided with electrical leads 42 and 43 extendingthrough a ring and brush arrangement 44 to the receiver 45. The

belt 36 carries a pair of equally spaced apart ber 58. However, when theelectromagnet-53 is.

actuated, it immediately disconnects the receiver 45 and insteadconnects the driver 25 through leads B and 6|.

In operation, the projector-detector member 58 is located approximatelyat the center of the harbor orother area being guarded. Thisprojector-detector member 58 is so mounted under water in the harborthat it can be rotated by a self-synchronous motor therein complementary4 leads 42 and 43 to operate the flash neon tube 4| and light the sameup momentarily. A spot of light will then be visible through the window40 on the dial face l4 at the point 40' which, by interpolation betweenth range circles 1,000 and 2,000, will show that the object that causedthe echo was at a range of 1,600 yards and an azimuth of north.

When the device is first set in a new area, the operator shouldcarefully train the device over the whole area and range eachecho-producing object in the area, plotting the same with a soft pencilor other marking means on the translucent dial face l4. If there is anecho-producing obstruction at an azimuth of, say 220 at a range of 3,000yards, he will mark thesame as indicated at 63. All other existingecho-producing objects "should likewise be plotted, such as at 64 and65,

etc; Thereafter, in using the device, any spot of to theself-synchronous motor 24. The motor 24 r is provided with suitablcontrols '(not shown) so that the supporting arm 26 may be directed atwill behind the translucent dial face l4, a pointer 62 fixed on arm 26and visible through a transparent annular ring 66 adjacent the dial face[4 showing the position of the supporting arm 26 at all times. Theprojector-detector member 58 is so arranged that when the pointer 62 isat the point marked .N., or north, on the dial I2, theprojector-detector member 58 will likewise be pointed North in theharbor, and rotation of the pointer 62 to any other azimuth will causethe projector-detector member 58 00 be correspondingly pointed. However,it has been found in practice that it is more desirable to useadditional oifshore echo ranging systems with the as-v sociatedindicators so spaced in th detector area as to permit the effectiverange of each equipment not to exceed 4,000 yards.

The belt 36 is rotated at such a speed that one window 40 will move fromthe zero position at the outside of the spot ion the dial to the 4,000

yard position at the outside of the dial face l4 in the same time thatit takesfor a sound sent out by the projector-detector member to make around trip from the projector-detector member 58 to a point 4,000 yardsaway; that is, the window 40 will take five seconds to move thisdistance because the under water speed of sound is 4,800 feet persecond. 7

. A boss 46 will contact the push button 41'to operate the switch 45just as adjacent window 40 is passingthe edgeof the spot I6. This willcause the switch 54 to connect the driver 25 and cause a supersonicimpulse to be projected by the projector-detector member 58. If thissound hits the under-water object itwill echo back and be received bythe detector portion of the projectordetector member 58. y Assuming fora moment that the object that re-echoed the sound was 1,600 yards fromthe projector, then the echo would reach the detector portion exactlytwo seconds after it was sent out, and the window 40 will be under thespot 40' on the dial face [4. The sound reaching the detector portionwill connect the detector portion through the lead 51, switch 54, andlead 56,130 the receiver 45. .Thus receiver45, which includes anamplifier, will cause .a circuit through: the

light produced at any of these known obstruction points can, of course,be ignored. However, should a spot of light appear anywhere on the dialsthat does not correspond to a known echoproducing obstruction, it willimmediately indicate the presence of some unknown object at that point,such as a submarine under water or in the darkness or fog, a ship orvvessel attemptingto enter the harbor. Once such an unknown echoproducingobstruction is located, it may be kept under observation by controllingthe selfesynchronous motor 24 and its path may be traced by marking witha different colored pencil the locations of the subsequent flashes thatappear. At the same time the operator'will set in motion anydefense'actions necessary to investigate, 'capture or obstruct theunknown submarine or vessel attempting to enter the guarded area.

When no unknown echo is produced the operator will keep. watchingoverthe harbor by slowly training the projector in all differentdirections, say a few degrees apart every five seconds. It will thus beimpossible for any submarineor other vesselzto enter under cover ofdarkness or fog without its presence and course or locationbeingimmediately detectable ,andplottable on the dial face I4, enablingproper defensive measures to be immediately undertaken. w i

Other modifications and changes in the number and-proportions of theparts may be made by those skilled in'the art without departing from thenature of this invention within the scope of what is hereinafterclaimed. I

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor. I

What is claimed is: Y r

1. A plotter indicator for a harbor or similar area comprising a soundprojector and detector located in the area, a range and azimuth plottingface, range and azimuth indicating means movable over said plottingface, means for ranging said indicating means oversaid plotting face incorrespondence with they underwater speed of sound means forsimultaneously training said sound projector and detector and saidindicator in identical azimuth, means actuated by said indicating meansto cause the sound projector to project a sound, andrneansjiinsaidfi'ndicating means jactuated by theechd of saidfproject'ed sound onsaid detector to actuate said indicating means to indicate bothrangeandazimuth on said plotting face simultaneously; i

2. A plotter indicator for atharbor or. simi ar area comprising a soundprojector and detector located in the area, a range and azimuth plottingface, range and azimuth indicating means mar-- able over said plottingmeans for ranging said indicating means over said plotting face incorrespondence with the underwater speed of sound, means actuated bysaid indicating means to cause the sound projector to project a sound,means in said indicating means actuated by the echo of said projectedsound on said detector to actuate said indicating means to indicate bothrange and azimuth on said plotting face simultaneously, and synchronousmotor means for simultaneously training both said projector and detectorand said indicating means in identical azimuth.

3. A plotter indicator for a harbor or similar area comprising a soundprojector and echo detector located in the area, a range and azimuthplotting face located in a convenient position, range and azimuthindicating means movable over said plotting face, means for ranging saidindicating means over said plotting face in correspondence with theunderwater speed of sound means for simultaneously training said sound Iprojector and detector and said indicator in identical azimuth, meansactuated by said indicating means to cause the sound projector toproject a sound, and means in said indicating means actuated by the echoof said projected sound on said detector to actuate said indicatingmeans to indicate both range and azimuth on said plotting facesimultaneously.

4. A plotter indicator for a harbor or similar area comprising a soundprojector and detector located in the area, a range and azimuth plottingface, range and azimuth indicating means movv projector and echodetector located in the area,

a range and azimuth plotting means located in a convenient position,range and azimuth indicating means forming part of said plotting means,means connecting said sound projector and echo detector to said plottingmeans causing said sound projector to project a sound which, whenechoed,

'jcctor and echo detector located in the area, a

range and azimuth plotting means located in a convenient position, rangeand azimuth indicating means forming part of said plotting means, meansconnecting said sound projector and echo detector to said plotting meanscausing said sound rojector to project a sound which, when echoed;

causes said echo detector to actuate said range and azimuth indicatingmeans of said plotting means, means for synchronously training theazimuth part of said range and azimuth indicating means over theplotting means and said sound projector and echo detector over the area,and means for operating the range part of said range and azimuthindicating means in accordance with the underwater speed of sound.

7. A method for detecting the location or pus-- sage of an unknownobject in a limited are" comprising selectivel projecting a sound overall the various portions of the limited area, plotting the range andazimuth of echoes produced by all known echo-producing objects withinsuch area, continuing to selectively project Sounds over the variousportions of the area and plotting any echoes whose range and azimuth donot agree with the range and azimuth of the echoes already plotted fromthe known objects to thereby detect an unknown object.

8. A method for detecting the location or passage of an unknown objectin a limited area comprising selectively projecting a sound over all thevarious portions of the limited area, plotting the range and azimuth ofechoes produced by all known echo-producing objects within such area,continuing to selectively project sounds over the various portions ofthe area and plotting any echoes whose range and azimuth do not agreewith the range and azimuth of the echoes already plotted from the knownobjects to thereby detect an unknown object and then continuing toselectively project sounds toward the unknown object and plotting anychange in the range and azimuth of echoes produced by such unknownobject to thereby reveal any change in the location of the unknownobject,

EARL W. SPRINGER.

